Characteristics Of Gear Transmission System Research Articles

Effect of Gear Tooth Cracks on the Dynamic Characteristics of Gear Transmission System of High-Speed Train

Abstract In order to study the dynamic characteristics of a high-speed train gear transmission system with cracks, time-varying meshing stiffness of gear teeth with different cracks was obtained using energy method. A torsional vibration model of the gear transmission system of a high-speed train was established. Based on the model, the ρ-value describing the change in stiffness was used to obtain the analytical solution of a system with crack faults. The influence of the degree of crack on the dynamic characteristics of a system under torque excitation of the driving end and load end was analyzed. In contrast with a normal gear system, a system containing a crack fault generated no harmonic response. Moreover, for a given set of working conditions, the degree of crack only affected the resonance amplitude and frequency of the system. These results form a robust guide for the detection of crack faults in the gear transmission system of a high-speed train.

Research on Nonlinear Vibration Characteristics of Internal Beveloid Gear Transmission System

The internal beveloid gear has good scientific research value and a broad application field. However, there is a lack of research on the nonlinear vibration characteristics of internal beveloid gears. The present study establishes a nonlinear vibration model that takes into account axial vibration, gear torsional vibration, and radial support vibration. The effects of various excitation parameters on the vibration characteristics of the gear transmission system are analyzed and computed using the Runge–Kutta method. After analyzing the dynamic model of the gear pair using numerical methods, the harmonic balance method is employed to obtain the theoretical analytical solution for a single−stage gear. The obtained results are compared with the velocity and acceleration time−domain response curves obtained from the numerical method, and they show excellent agreement.

Study on nonlinear vibration and primary resonance characteristics of helicopter face gear-planetary gear coupling transmission system

In order to explore the dynamic response and primary resonance characteristics of the gear transmission system of the helicopter main reducer. The face gear-planetary gear torsion-translation vibration dynamics model is established, and the time-varying meshing stiffness, gear backlashes, gear eccentricity error, and friction are considered. The four-order variable-step Runge–Kutta was used to solve the dynamic response of the system, and the nonlinear dynamic characteristics of the system were described by time domain diagram, phase trajectory plane, Poincaré map, 3D frequency spectrum, and bifurcation diagram. Additionally, using the face gear-spur gear system's transmission as an example, the multi-scale method is used to analyze the face gear-spur gear system's primary resonance characteristics. The influence of load fluctuation amplitude, meshing damping, and meshing stiffness on its amplitude-frequency characteristics is also investigated. It is found that when external load excitation frequency changes, the vibration response of the whole system changes synchronously, which exhibits periodic, multi-periodic, and chaotic motion. In addition, according to the primary resonance analysis, the system's stability will be harmed by increasing the external load fluctuations’ amplitude, lowering the meshing damping, and raising the meshing stiffness.

Research on Meshing Gears CIMT Design and Anti-Thermoelastic Scuffing Load-Bearing Characteristics.

In the process of gear meshing, it is an inevitable trend to encounter failure cases such as contact friction thermal behavior and interface thermoelastic scuffing wear. As one of the cores influencing factors, the gear meshing contact interface micro-texture (CIMT) significantly restricts the gear transmission system (GTS) dynamic characteristics. This subject suggests the contact characteristic model and interface friction dynamics coupling model of meshing gear pair with different CIMT. Considering the influence of gear meshing CIMT on distribution type of hydrodynamic lubricating oil film, contact viscous damping and frictional thermal load, the aforementioned models have involved transient meshing stiffness (TMS) and static transmission accumulated error (STAE). Based on the proposed models, an example verification of meshed gear pair (MGP) is analyzed to reveal the influence of CIMT on the dynamic characteristics of GTS under a variety of micro-texture configurations and input branch power and rated speed/shaft torque conditions. Numerical simulation results indicate that the influence of CIMT on gear dynamic response is extremely restricted by the transient contact regularity of the meshing gear surface. Meshing gears’ dynamic characteristics (especially vibration and noise) can be obviously and effectively adjusted by setting a regular MGP with CIMT instead of random gear surfaces.

Meshing impact analysis of planetary transmission system considering the influence of multiple errors and its effect on the load sharing and dynamic load factor characteristics of the system

The meshing impact on transmission system and internal meshing gear pair and its impact on the load sharing and dynamic characteristics of the system are not well understood yet. In this paper, the meshing impact models of internal gear pairs and planetary transmission system were successfully constructed, and the meshing impact point, meshing impact time and meshing impact force were accurately obtained. Meshing impact in gear transmission system is obviously affected by eccentricity error, installation error, and other errors. Due to the difference in error of each component, the internal and external gears of each branch lead to different meshing positions, which causes the constant change in meshing impact point, meshing impact time and meshing impact force. This creates difficulties in the analysis of meshing impact characteristics of gear transmission system. Load Tooth Contact Analysis (LTCA) method can be used to accurately analyse the change in position of gear tooth under load condition. Through the dynamic model of planetary transmission system, the influence in component errors on the contact position of tooth surface is obtained. Combining the loaded transmission error of the tooth surface under load and the geometric transmission errors under the influence of component errors, the model of meshing impact for accurately solving the system is deduced, and the influence of meshing impact on the system's load sharing coefficient and dynamic load factor coefficient is analysed. By comparing the planetary transmission system before and after considering the meshing impact of the system, it is found that the system's load-sharing coefficient increases slightly, dynamic load factor coefficient fluctuates significantly, and meshing force becomes more clutter after considering meshing impact.

Effects of gearbox housing flexibility on dynamic characteristics of gear transmission system

The lightweight design of the gear system is the current tendency. The gearbox housing is modeled as a rigid body and is neglected in the gear dynamic analysis. It is of great significance to introduce the gearbox housing flexibility into the dynamic analysis and analyze the influence of the gearbox housing flexibility on the dynamic behaviors of the gear transmission system, as this can provide important instructions for the lightweight structure design of the housing. The gear–rotor–bearing model and the gear–rotor–bearing–housing model are established by the finite element node method. A Timoshenko beam element is used to represent the shafts. To illustrate the housing effect, two kinds of housing model are established: one tends to be rigid and the other to be flexible and lighter. The housings are simplified as a super element obtained by the dynamic substructure method. Natural frequencies and dynamic responses are illustrated to indicate the effects of housing flexibility. Comparisons of numerical results show that the rigid housing can be neglected for its little effect on the dynamic analysis. The flexibility of the housing slightly reduces the natural frequencies of the gear transmission system, and the maximum reduction is 6.05%. Meanwhile, the amplitudes of the first two resonance peaks of the dynamic transmission error decrease by 9.5% and 5.05%. Besides, more response peaks emerge at higher speeds when the flexibility of housing increases. The complete phenomena of dynamic behaviors of the gear transmission system can be obtained by considering the housing flexibility.

Investigation on the influence of heat on the dynamic characteristics of a gear transmission system

In order to study the influence of heat on dynamic characteristics of gear transmission system, the meshing thermal stiffness of gear was proposed, and it was introduced into the system dynamics equation. Meanwhile, the equivalent viscous damping of the system was studied by using the Coulomb friction damping model. Thus, the thermal dynamics model of system was established. In this article, the thermal dynamics model of gear system was established and solved. The comparative analysis of the thermal dynamic response and elastic dynamic response of the system was also provided. The results show that the maximum peak value, vibration velocity, and equilibrium position of thermal dynamic response are all bigger than those of the elastic dynamic response. The maximum dynamic load is found at the alternating point of double teeth region to single tooth region, and the maximum thermal dynamic load and thermal dynamic load coefficient are smaller than those of the elastic system because of the increases of the equivalent viscous damping. Additionally, the theoretical model is verified by finite element method and experimental method, respectively.

Noise Prediction of Traction Gear of High-Speed EMU Base on Acoustic-Structural Coupled Method

The dynamic characteristics of traction gear transmission system have great influence on the safety, comfort and reliability of EMU. Base on acoustic-structural coupled theory, the noise radiation characteristics of gear transmission system in high-speed train CRH380A are studied by finite element-boundary element method. The acoustic radiation analysis model is built by using acoustic BEM. The radiated noise is predicted by Helmholtz boundary integral equation. The research results can provide a theoretical basis for the optimization design of the low noise gear in EMU.

On thermal calculation for helical gear transmission system

The purpose of the study in the paper is to evaluate the thermal comportment of the transmission systems with helical gears. Also, the influences of heat on characteristics of gear transmission system, based on the meshing thermal stiffness of gears are analyzed. An experimental testing stand of the system will be used to obtain data. The respond of the transmission under different working conditions is also analyzed. The study concerns the comparison of theoretical results obtained using calculation methods (from literature) and the experimental results, in order to obtain an evaluation of the friction in the meshing gears. The heat (temperature) affects the dynamic characteristics of the system by the meshing stiffness of the gear. The experimental results are used to verify the correctness of the theoretical model.

Experimental study on thermal dynamic characteristics of gear transmission system

In order to study the influences of heat on dynamic characteristics of gear transmission system, the thermodynamics equation of torsional vibration of gear transmission system was derived based on the meshing thermal stiffness of gears. Meanwhile, an experimental platform for vibration testing of the system was established. The dynamic responses of the system under different working conditions were tested. The effects of load, rotational speed and heat on the dynamic characteristics of the system were studied by comparing and analyzing the experimental data, and the influence mechanism of the heat on the dynamic response was also studied. The results show that the load and rotational speed are the main factors that affect the dynamic characteristics of the system; the larger the system load, the larger the amplitude of vibration response, and similarly, the higher the rotational speed, the larger the amplitude of vibration response. The heat (temperature) affects the dynamic characteristics of the system by changing the involute characteristic and the meshing stiffness of the gear. When the initial temperature of the gear is lower than the calibration temperature, with the increases of the temperature, the vibration amplitude of the system decreases first and then increases. However, the natural frequency increases first and then decreases. Both of them showing a nonlinear variation. The experimental results effectively verify the correctness of the theoretical model.

Dynamic characteristics of wind turbine gear transmission system with random wind and the effect of random backlash on system stability

In order to study the dynamic characteristics of gear transmission system of wind turbine with random wind and the effect of random backlash on system stability, a stochastic volatility model is established to obtain the external excitation of gear transmission system of wind turbine. A dynamic model of system is set up with the consideration of gear time-varying mesh stiffness, transmission error and backlash. The dynamic behavior of system with random wind and the effect of random backlash on system stability are obtained using numerical method. The results show that: (1) The vibration displacement of system components has the similar trends with external excitation, and the higher the speed, the greater the vibration displacement. (2) Random backlash has a significantly influence on system stability. The instability of system decreases at first and then increases with the increase of mean backlash, and the stability of system decrease with the increase of standard deviation of backlash. The operation stability of a wind turbine will improve if select an appropriate gear backlash.

Optimisation analysis of gear transmission system of the automobile gearbox based on the MASTA software

The dynamic meshing characteristics of gear drives have been a major concern in the design of gear transmission system. The paper takes a five-speed gearbox as an example to accomplish the gear mesh analysis based on the MASTA software. According to the transmission characteristics of gear transmission system of the automobile gearbox, the simulation modelling of the gearbox is built to determine a reasonable configuration of the overall gearbox, and then simulate the actual load conditions and complete the process analysis for the gear. The computational results show that using the specialized software MASTA for transmission modelling and simulation analysis can heavily improve the design level and mechanical properties of the gearbox. It is a useful work for the industry to employ the powerful MASTA to design gearbox from the whole system approach. In conclusion the present work can provide effective guidance for the fault diagnosis of gear meshing.

Vibration and Noise Radiation Characteristics of Gear Transmission System

This paper presents a comprehensive procedure to calculate steady dynamic response and noise radiation generated by a gear reducer. In this process, the bearing force is obtained by solving the transmission system dynamic model, which is taken as the excitation of the gearbox, the noise generated by the gearbox vibration is researched by using FEM/BEM, so the dynamic characteristics of gear transmission and gearbox structure are demonstrated. Then the time history of node dynamic response and noise spectrum of the gearbox are obtained, and the effect of the excitation of frequency doubling of mesh frequency on the gearbox vibration and noise radiation is illustrated. The changes in radiated noise of gear reducers with load are calculated respectively by using both simulation and Kato's formulae, and results agree well with each other. The frequency range of the gearbox resonance is obtained by analyzing the spectral maps of the vibration and noise under the case of engine speed steadily increased. The study provides useful theoretical guideline to the design of the gearbox.

Analysis of Dynamic Characteristics of Gear Transmission System Based on Wind Turbine Gearbox

Based on gear transmission system of 1.5MW wind turbine, dynamic characteristics are analyzed under the effect of both external and internal incentives. Using lumped parameter method, the dynamic model involving 6 degrees of freedom for every helical gear is established with taking the time-varying mesh stiffness and error into account. The results show that the transmission system is quasi-periodic under the operating speed, and the vibration direction of gear with a large amplitude is obtained. This study can be referred to the engineering applications.

The Gap Nonlinear Characteristics of Gear Transmission System under External Excitation

For the study of nonlinear dynamic characteristics of a pair of gears in an external torque under gear meshing error excitation, we will establish two degrees of freedom nonlinear torsional vibration model. The use of Matlab / Simulink for numerical simulation solves the nonlinear dynamic model of the gear gap. Study the dynamic characteristics of the system in a certain domain of parameters on external incentive conditions, as well as external motivation of gear transmission system dynamic characteristics influence. The results have important practical value for future engineering practice on gear transmission system's dynamic design, and have important theoretical significance for complex gear transmission system dynamics study.

Dynamic Characteristics of Gear Transmission System for Wind Turbine Gearbox

A study is made on gear transmission system of 1.5MW Wind Turbine Gearbox. Using lumped parameter method, the dynamics model involving 6 degrees of freedom for every helical gear is established with taking the time-varying mesh stiffness and error into account. The dynamics characteristic of transmission under the effect of both external and internal excitation is calculated. The results show that under the rated speed, the transmission system is quasi-periodic, and the vibration directions of gears with large amplitude are obtained, which is consistent with testing results. This study can be referred to in engineering applications.

An Improved Method to Calculate the Meshing Stiffness of Helical Gear

The meshing-stiffness of a helical gear pair is one of important parameters to study dynamic characteristics of gear transmission system. However, the equation to solve the meshing stiffness is very complex and difficult to get it. We put up with an improved method to quickly calculate the meshing stiffness through analyzing the meshing process and characteristics of the helical gear pair. The obtained time-variant meshing stiffness curve matches the theoretic stiffness curve very well. The result is shown that the method for calculating contact line based on the helical gear engagement process and characteristics, can be understand intuitively and easily.